Oxidation of aromatic compounds: XV. Oxidation of arylacetylenes in a system HF-PbO2
摘要:
The oxidation of symmetrically substituted diarylacetylenes ArC CAr (Ar=C6H4R) containing strong electron-withdrawing groups R=4-COMe, 4-CO2Me, 3-CO2Et, and 4-NO2 in a system HF-PbO2 at -10 divided by-20 degrees C led within 0.5-3 h to the formation of Z,Z-1,2,3,4-tetrakis(aryl)-1,4-difluorobuta-1,3-dienes ArFC=C(Ar) ( Ar)C=CFAr. The butadiene structures obtained exist in solutions as s-cis- and s-trans-conformers and in the crystalline state are present in the stable s-cis-form.